Complexation of α-ferrocenylmethylcarbenium tetrafluoborates by ethers; an NMR study

The tetrafluoborates of the primary, secondary, and tertiary ferrocenylmethyl carbenium ions have been prepared from the corresponding carbinols in ethyl ether, tetrahydrofuran and t-butyl methyl ether by adding HBF 4 . The NMR spectra of these salts, which dissolve in CDCl 3 , are characterized by the presence of very strong signals attributed to the ether used in the preparation, the solubility depending upon the structure of the cation and that of the ether. The NMR data suggest that α-ferrocenylcarbenium ions undergo two distinct types of solvation with ether-like donor molecules: one involves a much stronger interaction than the other.